Hi all,
I've been reading here for a while, and have been really impressed with the participation and quality of information. Very nice forum! With my bathroom remodel underway now, I have the first few initial questions (with likely more to follow along the way). First, here's a quick summary of the project. Iíd be glad to supply any additional details, and/or pics, but didnít want to overdo the first post.

I'm remodeling a very small bathroom that my wife (the project director) wants to create the impression of being larger than it is. So, Iíve already removed the bathroom doorway, and enlarged the opening up to the ceiling, and cut the wall opposite the shower to a stub (containing the sink drain). Also changed the electrical to move and add lights. With that work now completed, next comes the floor of the bathroom/hall/closet(s). The boss wanted all marble floors (12x12), so thatís what it will be. The tiles will be in a diamond pattern, spaced at 1/16Ē. Iíve taken the time to lay out tile in order to get the best looking pattern, and have the exact coordinates of the first tile. Iím now ready to install Ditra (not heated) using Versabond over a very solid plywood floor, and feel comfortable about that first step. So here are the questions.

1) I know unmodified thinset is used for the tile, and have read that Home Depot does not sell the right product for this job. Does anyone have a strong preference on the right thinset for 12x12 marble on Ditra? Something from Lowes would be the easiest, but Iíll travel to a tile store if none of the box stores sell the right stuff.

2) Iíve seen 2 different trowel size recommendations for the tile thinset, so Iím looking for opinions on which trowel size is best for 12x12 marble on Ditra.

3) Iíve done a few tiling jobs, but have never used Ditra or marble tile. I know about using unsanded grout and being careful to not scratch the tile before sealing it. And of course I'll need to be extra careful to avoid any lippage that bare feet would be sure to feel in a bathroom. Beyond that, are there any other special considerations about marble tile on Ditra that I need to be aware of?

4) The last part of this project will be a shower, to be built next Spring. I know that it would be much better to do the shower before the floor, but time constraints donít allow it to happen that way. So Iím planning on leaving a 1/4Ē gap between the tiles and the current fiberglass curb, in order to avoid disturbing the floor when I remove the fiberglass shower. I know itís going to be something of a PITA to get that shower out, but Iíll make certain to protect the floor from damage during the shower project. Iíve also considered leaving out the tiles adjoining the shower curb, but donít feel thatís necessary. Any concerns related to running the tiles right up to the existing shower with a small gap?

And, of course Iíd be open to other suggestions or comments on anything related to this project that I havenít mentioned above. Thanks in advance for taking the time to read this long post!

Before we get too far in, let's stop right here and evaluate the floor system. First, any natural stone needs a floor twice as strong as what is required for ceramic tile. Very few floors meet this requirement without some work. Stone also requires two layers of plywood. Do you have that?

Start by plugging your joist specs into the Deflecto in the blue bar above and see what you come up with.

Kevin,
Thanks for the reply. I'll admit to taking an intuitive route on the structure, for the following reason. The house is a 25 year old modular with 2x6 framing. It was trucked here to MA from PA, as 4 separate 'boxes'. So this bathroom is located in one of the two second floor boxes, stacked on top of a lower box.

The shortcut I took was to rely on what the modular company had told us when we were buying the house. They stated the need to overbuild everything, in order guarantee they could successfully make the trip and complete the setting of the house, and also to insure they would comply with the toughest state and local building codes they would encounter. And nothing during the past 25 years would lead me to believe the house is less than rock solid.

However, I'm certainly willing to reconsider this, based on what you posted. I'll need to dig through the plans for the house and see if I can find the specific specs for our unit. Much of the plans we received consist of generic specs, which applied to all of their homes. I'll take a look and see what I can find out.

Well, it appears that it wouldn't be as simple as plugging numbers into the calculator (but why should I expect anything to be simple with these DIY projects). Turns out that the (10") floor joists are 12" OC for most of the bathroom, with the exception of the one at the outside wall being 16". OTOH the large closet and the 8'x4' hallway space connecting that closet to the bathroom are all 16" OC.

But, before taking this any further, I had another discussion with the boss about the whole marble idea. I'll freely admit to not being happy or comfortable about that material from the get go. I've been having nightmares about cracked tiles, and flying through the air after slipping on wet marble. But my better half had her heart set on how it looks, and you guys are probably familiar with the happy wife thing.

Anyway, after relating the conversation from this thread to her, she appears to (very reluctantly and grudgingly) now be considering something other than marble tile. Although yelling yippee out loud would be a major mistake, I can do this

So we're off to the tile stores next week to see if she can find something to be happy with in place of the marble. Fingers crossed about that actually happening, and I expect to post back once we're moving forward again.

I appreciate the input, and it's been more helpful than I might have ever imagined it could be!

Ok, I'm back on the job after taking time out for a bunch of other stuff (I told her that it would get done, but didn't say how long it would take).

So, as some of you previously indicated, we did find a very nice 12" porcelain that's close in appearance to the marble we had, and she is happy with it The tile is still much more slippery than I would like, so I'll just make sure to keep my deck shoes on in the bathroom.

I'm ready to install Ditra, followed by the tile,and have 2 questions remaining before beginning.

1) I was planning on using a set-rite toilet flange extender, in order to make up for the new floor height. However, out of curiosity, I unscrewed the flange from the floor, and discovered to my surprise that the waste pipe moves up freely about 1". I don't know why it wasn't secured tight down below, but I'm thinking that movement might help me out.

So the question is, would there be any problem with simply lifting the pipe and tiling under the flange? I'm asking because I read somewhere that too much slope on the waste pipe can be bad, and lifting the pipe will certainly increase the slope of a connected pipe (but I can't know by how much). The flange appears to still be flat when positioned on top of the tile, so that shouldn't be a problem. If someone can confirm it's ok to do that, then I'll just drill holes through the tile and use longer hold-down screws.

2) I was planning on leaving a 1/8" gap between the tile and the fiberglass shower, which will be removed next Spring. I was going to put some wax paper between the shower curb and the tile, keeping them completely separated to avoid the shower removal disturbing the tile. Any problems doing this, or does someone have a better idea?

1. I see no reason for you not to simply raise that flange and tile under it, Ed. Be nice to see the plumbing set-up under there, but I can't envision anything that would be seriously impacted by putting a little more slope in that section of your drain. Long runs of toilet drain with excessive slope can create problems and you'll need to be the judge of what could feasibly be under your floor. Or cut a hole and look.

It's usually easier to cut notches in your tiles while setting for the flange screws rather than having to drill through the tiles later.

2. You should be using a flexible sealant in that 1/8th" gap so it should be no problem at all to cut it out when you decide to replace the shower unit.